Several wire thread inserts for mounting in a receiving thread of a component are known in the prior art. They are for example described in U.S. Pat. No. 2,363,789, EP-A-0 140 812 and EP-A-0 157 715. Regularly, the outer diameter of the cylindrical walls of the wire thread insert has to be chosen slightly greater than the outer diameter of the receiving thread of the component. Therefore, mounting of the wire thread insert into the receiving thread of the component has to take place involving a diameter reduction of the wire thread insert. In this way it is ensured that due to the elastic re-deformation of the wire thread insert after installation into the receiving thread a tight fit of the wire thread insert is achieved.
A half coil at the end of the cylindrical helix of the wire thread insert is retracted radially inwardly in the known way (EP-B1-0 228 981) to facilitate the screwing-in of the wire thread insert into the receiving thread. The smallest outer diameter of the retracted section of the wire thread insert should approximately be equal to or slightly greater than the corresponding outer diameter of the receiving thread in the component. Further, the wire cross-section of this known wire thread insert is tapered at the end to facilitate the screwing-in of the wire thread insert into the receiving thread and to avoid damages at the thread bore in the component.
Different embodiments of wire thread inserts are also disclosed in EP-B1-0 983 445. Thereto belongs for example the wire thread insert 1 shown in FIG. 1 consisting of a cylindrical helix 2 having a plurality of helically wound coils 3. A first coil 4 of this cylindrical helix 2 leads to a mounting tang/installation tang 6 projecting radially straight into the cylindrical helix 2. The mounting tang 6 is gripped by means of a suitable installation tool and the wire thread insert 1 is screwed into the receiving thread of the component therewith. The mounting tang 6 is removed after completion of the installation as the mounting tang 6 is broken off by means of the predetermined breaking point 5 in the first coil 4. In this way, a receiving thread is formed having a continuous screw-mountable wire thread insert.
In this construction of the wire thread insert 1 it is especially a disadvantage that the mounting tang 6 has to be broken and removed. At the automatic installation of such wire thread inserts 1 it may even be necessary to record the broken and removed mounting tang 6. It is furthermore disadvantageous that the wire thread insert has to be mounted into the receiving thread of the component in a certain orientation. This is because the wire thread insert 1 has to be screwed-in into the receiving thread with the mounting tang 6 ahead.
A further wire thread insert 1 which is known from the prior art is shown in FIG. 2. In contrast to the wire thread insert of FIG. 1, the wire thread insert of FIG. 2 does not comprise a mounting tang. Instead, a moving groove 7 is provided in the first coil 4 of the wire thread insert. An installation tool of the wire thread insert engages this moving groove 7 to screw the wire thread insert 1 into the receiving thread of the component. The free end of the first coil 4 of the wire thread insert 1 is provided with a tapering 8 to support this screw-in process and also the entering of the wire thread insert 1 into the receiving thread. The construction of the wire thread insert 1 according to FIG. 2 permits only a very sophisticated automated mounting into the receiving thread of the component. The wire thread insert 1 is inserted by means of a preload cartridge at an automated assembly. The insertion requires an excessive monitoring of the process. Further, the wire thread insert 1 of FIG. 2 can be reduced in its diameter during the installation only restrictedly so that the wire thread insert 1 applies lower holding forces after the installation in the receiving thread took place compared to for example the wire thread insert 1 of FIG. 1.
Starting from the wire thread inserts of the prior art, the object of the present invention is providing a wire thread insert which is installable into a receiving thread of a component with lesser effort and more process reliable compared to the prior art. It is a further object of the present invention to provide a respective installation method, an installation tool, a manufacturing method and a manufacturing device for such a wire thread insert.